1、翻译部分英文原文Finite element analysis of three-way roadway junctions in longwall miningR.N. Singh, I. Porter, J. HematianFaculty of Engineering, Uniersity of Wollongong, Northfields Avenue, Wollongong, NSW 2522, AustraliaAbstract: This paper presents a three-dimensional finite element analysis of three-wa
2、y roadway intersections in longwall mining, and assesses the stable/unstable behaviour of three-way intersections under a range of loading conditions. Loads were applied to the model by means of uniform stresses on the internal free faces. This method of loading the model from the inside helped to r
3、educe its size and to eliminate the boundary effects. Stress concentrations and displacement results on the mid-height of the pillars, roof and floor strata adjacent to the three-way intersections and cut-throughs were calculated.Based on this study, guidelines for designing the support system for t
4、hree-way intersections are suggested. The results were validated by a case study of a three-way intersection in an underground coal mine in the southern coal fields of the Sydney Basin. Keywords:underground、 coal mining; gate roadway、; intersections; stability、; finite element method1. IntroductionA
5、 trend exists in Australia for installing high productivity longwall faces producing 3.04.0 milliontonne raw coal per annum per face. The mainconcern for the success of the high-production longwallfaces is to achieve high rates of developmentand to maintain stability of access roadways andtheir inte
6、rsections during the life span of the face.Intersections are formed when the pillars betweenthe two roadways are intersected by driving a crosscut. Roadway intersections in underground mines areparticularly susceptible to ground control problemsdue to inherently wide roof spans used and the difficul
7、ty in installing roof supports promptly inhighly mechanised headings. Stresses induced duringintersection formation may result in high incidenceof roof and rib failures. Despite many investigationsinto the stability of gate roadways intersectionsadverse conditionssuch as high horizontal stress and u
8、nsteady state ofabutment pressure from moving longwall faces maycause instability of gate roadway intersections.For example in 1985; major strata control problems inthe main gate of no. 6 longwall panel at WestcliffColliery resulted in roof fall, which stopped coalproduction for a period of 6 weeks.
9、 Similarly, a rooffailure incident at Pacific Colliery caused the longwallequipment to be buried resulting in stoppage ofthe longwall operations for a period of 3 months.Thus, unprecedented stratacontrol problems may have significant effects onoverall production from high-productivity longwallsystem
10、s even over a short duration.This paper containsan investigation of the application of a three-dimensionalfinite element method to calculate stressesand displacement around three-way roadway intersections.The effects of individual parameters such as depth of cover, the ratio of horizontal to vertica
11、lstress (K) and the width of opening on the stability of the three-way intersections are examined. Theresults are compared with the field observations at anunderground coal mine in the southern coal field ofthe Sydney Basin.2. Stability analysis of three-way intersections using three-dimensional fin
12、ite element modelsThe procedure used in the stability analysis of thethree-way intersections comprised of defining themechanical properties of the rocks surrounding theintersection, the geometry of the intersection and thevirgin state of stress. The stresses and displacements induced around the inte
13、rsections were computed usinga three-dimensional finite element method. Ifunstable conditions existed, either the design of supportsystem was changed or the geometry of thestructure was modified.Important input data forthese models were vertical stress and the ratio ofhorizontal to vertical stress K
14、 for a given lithologyand dimensions of the roadway intersection (see Fig.1).Assuming symmetrical conditions around a threewayintersection, only half of the structure wasmodelled using eight-node solid elements comprisinga total of 7190 elements and the 11 597 grid points.The computer running time w
15、as 17 h using around 1Gb of memory. The rock mass properties assigned tothe intersection model are presented in Table 1.The loads were applied to the Fig. 1. Plan and section of the finite element three-dimensional intersection modelTable 1 Rock properties assigned to three-way intersection modelsRo
16、ck typeThickness /mE /GPaMedium grain sandstone4.010.00.20Fine sandstone and mudstone3.06.00.25Coarse sandstone and shale2.03.00.20Top coal1.03.50.3Coal3.03.50.3Mudstone1.08.00.25Coarse sandstone4.012.50.2Medium grain sandstone5.010.00.2model by means ofuniform pressures on the internal free faces. Thistechnique of applying load from the inside helped to reduce the size of the model
